The ability to pattern cells, tissues, organisms, colonies, embryos, and other biological material, as well as non-biological material, at specific sites on a plate is important for many areas of scientific research and medicine. By placing such materials at known locations, researchers may study many samples under identical and controlled conditions, while monitoring each sample independently and repeatedly over time. Since each sample is in a known location, large numbers of samples may be studied, resulting in statistically significant data sets. Arrays of isolated biological media can be used to assist in diagnosis by observing the media under controlled conditions in the presence of unknown agents or pathogens.
To accomplish patterning of media, conventional technologies rely on three major strategies: (1) patterned surface treatments, (2) structured microwells, (3) physical stenciling, all of which have shortcomings overcome by this invention.
Patterned surface treatments create surfaces with specific chemistry at predetermined locations. This is performed by lithographic methods (i.e., UV radiation through a photographic mask), or by rubber stamp approaches, where chemicals are physically transferred to the plate surface by a patterned rubber stamp. The result of surface treatments is that regions are made favorable or unfavorable for media attachment (e.g., cell growth, protein binding). After incubation with the media, the media and buffer are washed away. These methods are not highly selective—patterning of the media is not particularly good, and each media/plate requires a different surface treatment specific to that media/plate combination.
Structured microwells may be patterned into the surface by lithographic etching or molding cavities in the surfaces. Such microwells are of limited use because cells will readily grow out of the cavities and media may readily coat all sides of the microwells. For best results, high aspect ratio wells are required (to contain the biological media), increasing manufacturing difficulty and cost.
Physical stenciling techniques use a rigid temporary barrier that is placed over the plate of interest. This barrier is in the form of a stencil or microfluidic device. Following this, media is introduced and allowed to attach to the surface at locations allowed by the stencil. After attachment, the stencil is removed leaving patterned media. This method suffers because it is difficult (and expensive) to produce stencils of high resolution, with large numbers of precision holes. The stencils must remain in intimate contact with the surface during the entire period of incubation (attachment). Generally, stencils leak between openings further reducing pattern resolution. Finally, such stencils are expensive, and a single stencil must be used for the entire incubation period for each surface that is to be patterned.
Therefore, improved methods and systems for patterning biological and non-biological material on specific sites on a plate would be desirable.